地月空间探测器星间测距自主定轨

Orbit determination of a cislunar space probe using Inter-Satellite Link data

地月空间导航、定位和授时均离不开探测器的精密轨道信息,目前在地月空间主流探测器精密定轨仍依赖地基测量,包括地基测距、测速和干涉测量等技术.星间测距技术已经在北斗等卫星导航系统中得到充分应用,测量精度高且易于实现.由于引力对称性,地球附近卫星仅利用星间测距不能实现自主定轨,而地月空间存在众多引力非对称性区域,可以实现基于星间测距技术的自主高精度定轨.本文推导了相对论框架下的地月空间探测器星间双单向测距数据处理算法;针对地月空间平动点和DRO等区域典型轨道探测器,利用仿真数据分析了基于星间测距的地月空间探测器定轨精度.分析结果表明,引力非对称性强弱和轨道动力学约束是影响地月空间探测器定轨精度的重要因素.仿真分析结果还表明,1 m精度的探测器星间测距可以实现优于10 m的地月平动点和DRO探测器定轨精度.引入地球MEO卫星后一方面可以提高定轨精度,另一方面也有利于平动点探测器的快速轨道恢复.

The navigation,positioning,and timing in the Earth-Moon space are inseparable from the precise orbit information of a spacecraft.At present,the precise orbit determination of a probe still mainly depends on ground-based measurement,including ground-based ranging,Doppler and interferometry.Inter-Satellite Link measurements have been fully applied in Beidou and other satellite navigation systems,with high accuracy measurements and easy implementation.Because of the gravitational symmetry,a spacecraft near the Earth cannot achieve autonomous navigation by only using InterSatellite Link data.However,several gravitational asymmetric regions are found in the Earth-Moon space,which can achieve autonomous navigation and high-precision orbit determination solutions based on Inter-Satellite Link data.The data processing algorithm is deduced.Considering typical orbits in the Earth-Moon space,different application scenarios are designed,and the orbit determination accuracy is analyzed using simulation data.The analysis results show that gravity asymmetry and orbit dynamics constraints are important factors affecting the orbit determination accuracy of probes orbiting the Earth-Moon libration points.The simulation results also indicated that the orbit determination accuracy can be better than 10 m with 1 m noise in the data.